Anosognosia Predicts Progression To Alzheimer’s Disease

People who were unaware of their memory loss, a condition called anosognosia, were more likely to progress to Alzheimer’s disease, according to a new study from the Centre for Addiction and Mental Health (CAMH). Those who were aware of memory problems were unlikely to develop dementia.

While memory loss is an early symptom of Alzheimer’s disease, its presence doesn’t always mean a person will develop dementia.

“If patients complain of memory problems, but their partner or caregiver isn’t overly concerned, it’s likely that the memory loss is due to other factors, possibly depression or anxiety. They can be reassured that they are unlikely to develop dementia, and the other causes of memory loss should be addressed,”

says lead author Dr. Philip Gerretsen, Clinician Scientist in CAMH’s Geriatric Division and Campbell Family Mental Health Research Institute.

Anosognosia And Mild Cognitive Impairment

In other cases, the partner or caregiver is more likely to be distressed while patients don’t feel they have any memory problems. In Alzheimer’s disease, lack of awareness is linked to more burden on caregivers.

Both unawareness of illness (anosognosia) and memory loss (known as mild cognitive impairment) can be objectively assessed using questionnaires.

The study, believed to be the largest of its kind on illness awareness, had data on 1,062 people aged 55 to 90 from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). This included 191 people with Alzheimer’s disease, 499 with mild cognitive impairment and 372 as part of the healthy comparison group.

The researchers also wanted to identify which parts of the brain were affected in impaired illness awareness. They examined the brain’s uptake of glucose, a type of sugar. Brain cells need glucose to function, but glucose uptake is impaired in Alzheimer’s disease.

Reduced Glucose Uptake

Using PET brain scans, they showed that those with impaired illness awareness also had reduced glucose uptake in specific brain regions, even when accounting for other factors linked to reduced glucose uptake, such as age and degree of memory loss.

As the next stage of this research, Dr. Gerretsen will be tracking older adults with mild cognitive impairment who are receiving an intervention to prevent Alzheimer’s dementia. This ongoing study, the PACt-MD study, combines brain training exercises and brain stimulation, using a mild electrical current to stimulate brain cells and improve learning and memory.

While the main study is focused on dementia prevention, Dr. Gerretsen will be looking at whether the intervention improves illness awareness in conjunction with preventing progression to dementia.

Philip Gerretsen, MD, PhD, FRCPC; Jun Ku Chung, BSc; Parita Shah, BSc; Eric Plitman, BSc; Yusuke Iwata, MD; Fernando Caravaggio, PhD; Shinichiro Nakajima, MD, PhD; Bruce G. Pollock, MD, PhD, FRCPC; and Ariel Graff-Guerrero, MD, PhD; for the Alzheimer’s Disease Neuroimaging Initiative
Anosognosia Is an Independent Predictor of Conversion From Mild Cognitive Impairment to Alzheimer’s Disease and Is Associated With Reduced Brain Metabolism
J Clin Psychiatry 2017 10.4088/JCP.16m11367

Image: Ben Koorengevel

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